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Home Networking Technical Info

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In case you're interested, here's some technical info on network protocols straight from the Microsoft Resource Kit.

Technical Stuff

The information below is not necessary to read!  It is only provided for those who want to see what the resource kit offers, or for those that like to read techno-babble :-)

From the Win98 Resource Kit by Microsoft

Microsoft TCP/IP Protocol

Microsoft Transmission Control Protocol/Internet Protocol (TCP/IP) provides communication across interconnected networks that use diverse hardware architectures and various operating systems. TCP/IP can be used to communicate with computers running Windows 98, with devices using other Microsoft networking products, or with non-Microsoft systems such as UNIX.

Microsoft TCP/IP in Windows 98 extends the functionality that Microsoft TCP/IP offered in Windows 95. In Windows 95, Microsoft TCP/IP provided the following elements:

• Core TCP/IP protocols, including the Transmission Control Protocol (TCP), Internet Protocol (IP), User Datagram Protocol (UDP), Address Resolution Protocol (ARP), Internet Control Message Protocol (ICMP), and Domain Name System Protocol (DNS). This suite of Internet protocols provides a set of standards for how computers communicate and how networks are interconnected.
• Support for application programming interfaces (APIs), including Windows Sockets and NetBIOS.
• TCP/IP diagnostic tools to detect and resolve TCP/IP networking problems, including arp, ftp, nbtstat, netstat, ping, route, telnet, tracert, and ipconfig, plus Windows-based Telnet and IP Configuration (winipcfg) utilities.
• Client for DHCP, for automatic configuration of computers running TCP/IP on networks that have DHCP servers.
• Client for WINS, for dynamic resolution of IP addresses to computer names on networks that have WINS servers.
• Point-to-Point Protocol (PPP) for asynchronous communication, as described in Chapter 19, “Remote Networking and Mobile Computing.”

With Windows 98, the following enhancements are added:

• Automatic private IP addressing by the client, as described in the section “Configuring IP Addresses Using Automatic Private IP Addressing” later in this chapter.
• Multihoming, as described in the section “Configuring Multihoming” later in this chapter.
• Windows Sockets 2 support, as described in “Enhancements to TCP/IP in Windows 98” later in this chapter.
• Support for IP Multicast (Request for Comments [RFC] 1112), including support for Internet Draft for IGMP version 2.
• Support for Internet Control Message Protocol (ICMP) Router Discovery (RFC 1256).
• Performance enhancements for certain types of high-speed, high-bandwidth networks. These include support for TCP Large Windows (RFC 1323), support for Selective Acknowledgments (RFC 2018), and support for TCP Fast Retransmit and Fast Recovery.
• DHCP enhancements, including address assignment conflict detection and longer timeout intervals.

Understanding IP Addressing

Each workstation needs an IP address to communicate on a TCP/IP network such as the corporate network or the global public Internet. The section “Configuring IP Addresses” later in this chapter describes IP addresses in more detail, but for now it is just important to understand that there are two kinds of IP addresses, globally unique IP addresses and private IP addresses.

• Globally unique IP addresses, which you can use on the global Internet.

  On the Internet, the Internet Assigned Numbers Authority (IANA) assigns groups of IP addresses to organizations. The organizations can then assign IP addresses within those groups to individual computers. This prevents multiple computers from having the same IP address.

  For a computer to be visible on the Internet, it must be reachable through a globally unique IP address.

• Private IP addresses, which you cannot use on the global Internet.

  The IANA has reserved a certain number of IP addresses that will never be used on the global Internet. You can use these addresses for computers that will never be used to access the Internet.

  In some cases, you can also use these addresses for computers that need partial connectivity to the Internet but do not need to be directly reachable from the Internet. For example, if you need only Web browsing and e-mail connectivity on a computer, that computer does not necessarily have to be directly reachable from the Internet.

  However, in order to enable computers to use private IP addresses, you must deploy a firewall with proxy or Network Address Translator (NAT) capabilities. A proxy or NAT sits between a private network (a network of computers using private IP addresses) and the Internet. The firewall has a globally unique IP address that can be used on the Internet. When a computer on the private network sends a packet to the Internet, the NAT substitutes the source IP address on that packet for the NAT’s own IP address. Thus, the packets appear to originate from the NAT.

  This configuration provides flexibility and a certain level of security: hosts on the Internet cannot directly send IP packets to the computer on the private network because they do not know and cannot use its IP address. The firewall can provide a level of administrative control for which machines and which applications can reach computers on the Internet, and vice versa.

  For more information about private IP addresses, see Request for Comments (RFC) 1918. For more information about NATs, see RFC 1631.

Depending on your needs, you can use either private IP addresses or globally unique IP addresses for each workstation. You could also use both a private IP address and a globally unique IP address if you have a multihomed computer (a computer that has two different adapters, each connected to a different network). For example, a workstation could be connected both to the corporate network (using an adapter that is configured with a private IP address) and to the Internet (using a dial-up adapter that is configured with a globally unique IP address). For information about multihoming and this type of special configuration, see the section “Configuring Multihoming” later in this chapter.

Regardless of the type of IP address you choose, you have two options for configuring the IP addresses:

• Dynamic IP addressing.

  With dynamic IP addressing, the IP address can be configured automatically. This method is much simpler, decreases your management time, and enables you to reuse IP addresses. It is recommended for all sizes of networks.

  In Windows 95, two types of dynamic IP addressing were available. For corporate networks, if there was a Dynamic Host Configuration Protocol (DHCP) server on the network, the computer could automatically obtain the IP address from the DHCP server. And for dial-up Internet connections, some Internet Service Providers (ISPs) automatically assigned your computer a dynamic IP address.

  Windows 98 provides a third option, automatic private IP addressing. This option is recommended for simple networks that have one LAN (subnet) and no DHCP servers. With automatic private IP addressing, if no DHCP server is available, the computer automatically assigns itself a private IP address. (If a DHCP server later becomes available, the computer obtains an IP address from the DHCP server instead.) Computers using private IP addresses can communicate only with other computers using private IP addresses, on the same subnet. They are not directly reachable from the Internet.

• Static IP addressing.

  With static IP addressing, you must manually configure the IP address.

Configuring IP Addresses

Every computer on a TCP/IP network is identified by a unique 32-bit IP address, which also specifies routing information in an internetwork. An IP address looks like this:

172.16.94.97

This is referred to as dotted decimal notation, with each eight bits of an IP address (called an octet) separated from the next eight bits by a period. An IP address is a single value that contains two pieces of information:

• The network ID, which is the portion of the IP address that identifies a group of computers and other devices that are all located on the same logical network.
• The host ID, which identifies a particular computer within a particular network ID. A host, or node, is any device that is attached to the network and uses TCP/IP.

Each host on the network uses the network ID and host ID to determine which packets it should receive or ignore, and to determine the scope of its transmissions (only hosts with the same network ID accept each other’s IP-level broadcasts).

The Internet community uses address classes to differentiate networks of various sizes. The network class can be determined from the first octet of its IP address. Table 15.1 summarizes the relationship between the first octet of an IP address and its network ID and host ID, using w.x.y.z. to designate the four octets of the IP address. As Table 15.1 shows, the value of the first octet determines which portion of the IP address will be the network ID and which portion will be the host ID.

For example, the first octet of the sample IP address 172.16.34.1 is 172. The w values portion of Table 15.1 shows that if the first octet has a value of 128-191, it is a Class B address. Thus, the sample IP address is a Class B address. Its first octet (172) is the network ID, and the remaining octets (16.34.1) are its host ID.

Note

The sample IP addresses used in this chapter are private IP addresses, not IP addresses that are valid on the global Internet.

The table also identifies the total number of network IDs and host IDs for each address class that participates in the Internet addressing scheme.

Table 15.1 IP address classes

Because the sender’s IP address is included in every outgoing IP packet, the receiving computer can derive the originating network ID and host ID from the IP address field. This is done by using subnet masks, which are 32-bit values that allow the recipient of IP packets to distinguish the network ID and host ID portions of the IP address.

The value of a subnet mask can also be represented in dotted decimal notation. Subnet masks are determined by assigning ones to bits that belong to the network ID and zeroes to bits that belong to the host ID. When the bits are in place, the 32-bit value is converted to dotted decimal notation, as shown in Table 15.2.

Table 15.2 Default subnet masks for standard IP address classes

The result allows TCP/IP to determine the host ID and network ID of the local computer. For example, if the IP address is 172.16.34.1 and the subnet mask is 255.255.0.0, then the network ID is 172.16 and the host ID is 34.1.

Subnet masks are also used to further segment an assigned network ID among several local networks. For example, a network using the Class B network address 10.100 is one of over 16,000 Class B addresses capable of serving more than 65,000 nodes each. But if this corporate network includes 12 international LANs with 75 to 100 nodes each, it is better to use subnetting to make effective use of 10.100 than to apply for 11 more network IDs. In this case, the third octet of the IP address can be used as a subnet ID, using the subnet mask 255.255.255.0, which splits this Class B address into 254 subnets: 10.100.1 through 10.100.254, each of which can have 254 nodes. Any of these network addresses could be assigned to the 12 international LANs in this example. Within each LAN, each computer is assigned a unique host ID, and they all have the subnet mask 255.255.255.0.

Note

All systems connected to the same local area network must have the same subnet mask.

Host IDs 0 and 255 should not be assigned to a computer; they are used as broadcast addresses that are typically recognized by all computers.

Windows 98 provides three methods of IP addressing:

• DHCP addressing, in which DHCP servers such as computers running Windows NT Server 3.5 or later automatically assign IP addresses to Windows 98 clients.
• Automatic private IP addressing, in which the computer automatically assigns itself an IP address.
• Static IP addressing, in which network administrators manually configure IP addresses for all the computers on the network.

Microsoft NetBEUI Protocol

Windows 98 provides the NetBIOS extended user interface (NetBEUI) protocol for compatibility with existing networks that use NetBEUI. Because NetBEUI is nonroutable and was designed for smaller LANs, you should use the TCP/IP or IPX/SPX-compatible protocol for enterprise-wide networks that require a routable protocol.

NetBEUI in Windows 98 provides two types of traffic:

1. Unreliable connectionless traffic, in which the sender sends packets to the receiver without setting up a connection and with no guarantee that the packets will arrive. NetBEUI connectionless traffic are used for name resolution, datagrams, and miscellaneous traffic.
2. Reliable connection-oriented traffic, in which the sender and receiver establish a reliable connection before sending data. NetBEUI connection oriented traffic is used for commands such as net use, net view, and net start.

NetBEUI in Windows 98 supports a NetBIOS programming interface that conforms to the IBM NetBEUI specifications and includes several performance enhancements. The NetBEUI module, Netbeui.vxd, is accessible through the NetBIOS interface.

If Windows 98 Setup detects NetBEUI during installation, it installs support for Microsoft NetBEUI automatically. If you are upgrading from a computer that did not have NetBEUI, Windows 98 does not automatically install it; however, you can add it at any time.

To install NetBEUI

1. In Control Panel, double-click Network.
2. On the Configuration tab, click Add.
3. In the Select Network Component Type dialog box, click Protocol, and then click the Add button.
4. In Manufacturers, click Microsoft, and then in Network Protocols, click NetBEUI, and then click OK.
5. Click OK. Setup copies files from your original installation media and prompts you to restart your computer.

The Advanced properties for NetBEUI affect only real-mode NetBEUI. These values are set dynamically for protected-mode NetBEUI.

To configure real-mode NetBEUI manually

1. In Control Panel, double-click Network.
2. On the Configuration tab, double-click the instance of NetBEUI that is bound to your network adapter.

   Note

   If your computer has multiple network adapters, an instance of NetBEUI appears for each network adapter. You must configure each adapter with its own settings.

   The Bindings tab shows which clients and services are currently using the NetBEUI protocol. For information about configuring bindings, see “Configuring Network Adapters” later in this chapter.

3. Click the Advanced tab to modify settings for Maximum Sessions and NCBs for the real-mode NetBEUI. The following list outlines the options in NetBEUI advanced configuration.

4. Click OK. Then shut down and restart the computer.

IPX/SPX-compatible Protocol

The Microsoft Internetwork Packet Exchange/Sequenced Packet Exchange (IPX/SPX) – compatible protocol (nwlink.vxd) supports the 32-bit Windows Sockets 1.1 programming interface, so that any Win32-based Windows Sockets 1.1 application can run on IPX/SPX with Windows 98. (There are no 16-bit Windows Sockets applications using IPX/SPX.)

The IPX/SPX-compatible protocol can be used by Client for NetWare Networks to communicate with NetWare servers or computers running File and Printer Sharing for NetWare Networks.

This protocol can also be used by Client for Microsoft Networks to communicate with computers running Windows for Workgroups 3.11 or Windows NT that are also running IPX/SPX.

The IPX/SPX-compatible protocol uses the nwnblink.vxd module to support computers that use NetBIOS over IPX and to support the NetBIOS programming interface. This protocol can also use NetWare servers configured as routers (and other IPX routers) to transfer packets across LANs.

Configuring the IPX/SPX-compatible Protocol

The Microsoft IPX/SPX – compatible protocol is installed automatically when Client for NetWare Networks is installed. You can also install this protocol to support other network clients, including Client for Microsoft Networks.

To install the IPX/SPX-compatible protocol

1. In Control Panel, double-click Network, and then click Add.
2. In the Select Network Component Type dialog box, click Protocol and then click the Add button.
3. In Manufacturers, click Microsoft, and then in Network Protocols, click IPX/SPX-compatible Protocol, and then click OK.
4. Click OK. Setup copies the files you need.

When you install the IPX/SPX-compatible protocol, Windows 98 automatically detects and sets appropriate values for the frame type, network address, and other settings. However, in some cases you might need to configure settings for this protocol manually.

To configure the IPX/SPX-compatible protocol

1. In Control Panel, double-click Network.
2. Double-click the instance of IPX/SPX-compatible Protocol that is bound to your network adapter.

   Note

   If the computer has multiple network adapters, the list will contain an instance of the IPX/SPX-compatible protocol for each network adapter. You must configure each adapter with its own settings. You can only have four instances of IPX/SPX on your system, so if you have more than four adapters are installed, you should bind IPX/SPX only to the adapters that will use this protocol.

3. Click the Advanced tab.
4. Most values have correct defaults in typical installations. If you need to change a value for a particular purpose, select the item in the Property list and specify a setting in the Value list based on the information in the Table 15.10.

Table 15.10 IPX/SPX configuration values

You should not need to change bindings in most circumstances. However, you can disable the bindings for a protocol if you do not want other computers using that protocol to see this computer. At least one protocol, however, must be bound to the network client for the computer to communicate with the network.

[ Home Networking Part One ] [ Home Networking Part Two ]

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Last Revised: 01/04/2001

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